This is what I worry about with all the crazy deer around here. I swear they're lying in wait for me by the side of the road.
As for small animals my rule is try to avoid them - but not too hard. Don't put yourself in any jeopardy.

A couple weeks ago the guy in front of me going 35mph on a long downhill took out a deer. I saw the deer in the opposite lane and as soon as the deer saw us, it bolted directly in front of the guy. The rider was ok but pretty bruised and battered and the deer ran off. I was able to move over a little and miss the whole mess.

I ran over a big snake on my bike the other day. I was going fairly fast... I reacted fast enough to lift the front wheel over it, but I have to think my 210 lbs on a 23mm rear tire was a bit.... bad for Mr. Snakey.

Almost hit a turkey this spring. I was going ~ 25 mph. It would have been ugly. It also would have been ironic if a turkey killed me, considering how many of them I've kilt.

Hit a cat on my motorcycle way back when. Luckily I was going in a straight line.

I ran over a small rat that jumped in front of me riding home at 11 PM on the MUP. I knew it was a rat because the only thing I saw was the long tail. I felt bad and hoped that I only ran over the tail. I stopped and went back only to discover that it probably died quickly. There was no animal residue on the bike when I looked at home. Oddly enough, a coworker two offices away (I work at a 15k person company) found the rat the next morning. By the time I biked in late morning, someone had removed the body, but the dried spot was visible for three months until the first late fall rain. I felt bad for the poor critter and still apologize when I ride by that spot.

coasting, few quotes are worthy of him, and of those, even fewer printable in a family forum......quote 3alarmer
No @coasting, you should stay 100% as you are right now, don't change a thing....quote Heathpack

There is a large flock (herd) of canada geese that live by the side of a pond I frequently ride past. A few weeks ago a large female (she had a brood nearby) was smack in the middle of the narrow lane and I was coming right for her. I saw her and started to holler and flap (in a dignified way) thinking she would get out of the way if she saw me coming but she just stood her ground, stared me down and forced me to swerve. I've got to think that hitting a large bird like that would result in a bad outcome for everyone involved.

I ran over a big snake on my bike the other day. I was going fairly fast... I reacted fast enough to lift the front wheel over it, but I have to think my 210 lbs on a 23mm rear tire was a bit.... bad for Mr. Snakey.

Could be bad for you too. I've heard stories of guys hitting rattlers and the wheel kicking up a possibly dying but still very po'ed snake into their laps. Not much fun to be kissed by a snake in that sensitive spot I imagine!